From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Ignition advance curve for the Goshawk II engine governor.
| Identifier | WestWitteringFiles\H\April1922\ Scan40 | |
| Date | 20th April 1922 | |
| To E.{Mr Elliott - Chief Engineer} from EFC. c. Hy.{Tom Haldenby - Plant Engineer} c. EP.{G. Eric Platford - Chief Quality Engineer} EFC2/T20.4.22. X.4354 - RE GOSHAWK II IGNITION - GOVERNOR. Answering your E4/M18.4.22, the curve of advance marked A, was drawn from very definite figures given to us by EP.{G. Eric Platford - Chief Quality Engineer} as the result of careful dynamometer tests. We were aware of the figures given by Mr. Hives and had used them in our work, but the two limits which he gave were so wide apart that in any case the advance curve could easily be made to lie between them, and therefore we worked to something which was a little more definite. Your curve of average advance plotted from Mr. Hives' figures only shows a cam advance of 10°, and it would have been more appropriate to have made it agree with 12° advance (as for the other curve) at the top, i.e. to raise the curve vertically through 2°. Then the difference between this and EP{G. Eric Platford - Chief Quality Engineer}'s curve would be quite small in comparison with the Ms. limits. The idea of altering the ratio had occurred to us, only we wished, if possible, to attain the desired end without making too big an alteration to your design. We agree that with the alteration to the ratio, a curve of advance nearly equally as good as the best we have obtained, is obtainable, and we have no objection to this alteration if it is considered the cheaper for production in the long run. At the same time we have a note from Mr. Hives in which, referring to the Goshawk out there, he makes the following remark:- Contd. | ||